Interconnection between multi-layer ceramic substrates containing plated thru holes and printed circuit cards has been achieved employing solder ball connections. Typically, a process employing solder ball connection involves attaching 90/10 Pb/Sn solder balls onto the bottom side pads (I/O pads) of the multi-layer ceramic substrate. The solder balls are typically attached employing a eutectic solder, such as a 63/31 Sn/Pb solder. In this way, the solder ball connection module having balls attached thereto, then directly gets attached onto plated thru holes of the printed circuit card, using a reflow process. Typical reflow processes include vapor phase, electroforming process, or an infrared heating process.
However, the relatively low melting eutectic solder tends to flow into the plated thru hole, thereby deleting the same at the joints between the high melting solder ball/module pad, and solder ball/plated thru hole land on the circuit board or card. This, in turn, adversely affects the reliability of the device and provide for potential exposure of electrical opens.
The problem is especially exacerbated by subsequent processing whereby the card goes through subsequent wave solder processing to attach backside components. The wave soldering process in turn can remelt the low melting solder. The flow of the low melting solder during the process into the plated thru hole is referred to as wicking.